Gravity wave variations in the polar stratosphere and mesosphere from SOFIE/AIM temperature observations

Abstract

A 6 year (2007)(2008)(2009)(2010)(2011)(2012)(2013) temperature data set from the Solar Occultation for Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite is used to extract gravity waves (GWs) in the polar stratosphere and mesosphere of both hemispheres. These data are continuous in the polar regions. The monthly mean GW potential energy (PE) increases exponentially with a scale height of~13 km in the upper stratosphere and mesosphere. GWs are stronger in the winter than in the summer and exhibit strong annual variation. GWs are stronger in the southern polar region (SPR) than in the northern polar region (NPR) except in the summer months. This is likely because there are stronger and longer-lasting zonal wind jets in the SPR stratosphere, as revealed from Modern-Era Retrospective analysis for Research and Applications (MERRA) wind data. The longitudinal variations of PE in the winter polar stratosphere are consistent with the elevated regions. In the mesosphere, the longitudinal variations of PE do not vary with height significantly. The correlations between GW PE and the column ice water content (IWC, an indicator of the polar mesosphere cloud) exhibit longitudinal and annual variations.

Effects of Horizontal Wind Structure on a Gravity Wave Event in the Middle Atmosphere Over Syowa (69°S, 40°E), the Antarctic

“…These results are consistent with the results from previous studies in the Antarctic region (Kaifler et al, 2015;Kogure et al, 2017;Liu et al, 2014;Zhao et al, 2017). This value increased by 2-3 times at each 10 km of altitude increase between 40 and 60 km altitudes, and the winter (June to August) mean values at each altitude were 2-3 times larger than those of the fall (March to April) and spring (October) periods.…”

Variations of global gravity waves derived from 14 years of SABER temperature observations

“…We note that the latitude range of prominent positive trend of RPE is also consistent with the GW's hot spot region in the Southern Hemisphere, where GW RPE is larger than at other latitudes during the southern winter months. These strong GWs are believed to be associated with orography, polar stratospheric night jets, and planetary wave breaking around the polar vortex [ Wu and Eckermann , ; Preusse et al ., ; John and Kumar , ; Hoffmann et al ., ; X. Liu et al ., ]. Here we can analyze the zonal wind and its trend around the polar vortex to get some possible explanations on the positive trend in GWs.…”

“…It is generally accepted that the GWs in the stratosphere and mesosphere are related to the GW sources (orography, convection, jet/front systems, and planetary wave breaking) and propagation conditions (background winds and atmospheric stabilities) [ Nappo , ; Fritts and Alexander , ; Hertzog et al ., ; Jiang et al ., , ; John and Kumar , ; X. Liu et al ., ; Plougonven and Zhang , ; Thurairajah et al ., ; Ern et al ., ]. At the southern higher latitudes, the GWs generated by orography are comparable to the nonorographic GWs on zonal average, as revealed by Hertzog et al .…”

“…[], and X. Liu et al . []. The detailed procedure for extracting GWs from SABER temperature profiles is given in Appendix .…”

“…From Figure we can see that the GW PE in the stratosphere and lower mesosphere (30–70 km) is stronger at high latitudes of the southern winter hemisphere than in the northern winter hemisphere (note that the labeled tick below the x axis marks the 15 June of each year). This is consistent with previous observations from different satellite instruments [ Alexander et al ., ; Ern et al ., ; X. Liu et al ., ]. In the upper mesosphere and lower thermosphere (80–100 km), the hemispheric asymmetry of GW PE is not as obvious as that in the upper stratosphere or in the lower mesosphere.…”